Despite the widespread practice of basic and advanced life support, the vast majority of patients in cardiac arrest never survive to hospital discharge. The inherent mechanical inefficiencies of standard CPR limit the potential of even the most highly skilled rescuers. Moreover, the vast majority of cardiac arrest occurs in the home and delays to treatment severely limit the chances for survival. As a result, in the most efficient emergency medical systems, less than 15% of all patients with an out-of-hospital cardiac arrest are discharged from the hospital with intact neurological function. Furthermore, the average national survival to hospital discharge after out-of-hospital cardiac arrest, despite receiving standard CPR, is less than 5%. The goal of this SBIR application is to design and evaluate a novel device designed to increase the efficiency of standard CPR. This device is intended to optimize circulation in patients in cardiac arrest by giving the user the opportunity to actively compress and actively decompress the chest wall; it will act as an adjunct therapy to the inspiratory impedance threshold device (ITD), another technology that has been developed by the principal investigator. These two technologies combined will act to decrease the intrathoracic pressure during the decompression phase of CPR, creating a vacuum within the thorax relative to the rest of the body, thereby a) enhancing blood return to the heart, b) enhancing blood return to the brain, c) improving overall CPR efficiency, and d) providing real-time feedback to rescuers related to compression/decompression depth to maintain high quality CPR. The specific aims of this Phase I effort include: 1) prototyping three concepts for a novel active compression decompression CPR device, 2) assessment of the ergonomic issues of each concept and optimize a prototype design, and 3) establishing proof of concept by evaluating the prototype in an established porcine model for its ability to a) increase the short-term survival rate and neurological function, b) increase coronary perfusion pressure, and c) increase cerebral perfusion. These are important measures of the hemodynamic benefit that can be achieved over standard CPR. The proposed device is intended for home and professional rescuer use to increase the chances for meaningful survival after cardiac arrest. Of the 400,000 deaths occurring as a result of out of hospital cardiac arrest, it is estimated that an effective active compression decompression device in combination with the ITD can increase a victim's chance of survival by 5- 10%. This would result in 20,000 - 40,000 additional survivors per year. The intent is to develop and test a lightweight and ultimately disposable prototype device that can be used by both professionals and by the lay public.